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Cold agglutinin disease (CAD) is a rare, autoimmune, classical complement pathway (CP)-mediated hemolytic anemia. Sutimlimab selectively inhibits C1s of the C1 complex, preventing CP activation while leaving the alternative and lectin pathways intact. In Part A (26 weeks) of the open-label, single-arm, Phase 3 CARDINAL study in patients with CAD and a recent history of transfusion, sutimlimab demonstrated rapid effects on hemolysis and anemia. Results of the CARDINAL study Part B (2-year extension) study, described herein, demonstrated that sutimlimab sustains improvements in hemolysis, anemia, and quality of life over a median of 144 weeks of treatment. Mean last-available on-treatment values in Part B were improved from baseline for hemoglobin (12.2 g/dL on-treatment versus 8.6 g/dL at baseline), bilirubin (16.5 μmol/L on-treatment versus 52.1 μmol/L at baseline), and FACIT-Fatigue scores (40.5 on-treatment versus 32.4 at baseline). In the 9-week follow-up period after sutimlimab cessation, CP inhibition was reversed, and hemolytic markers and fatigue scores approached pre-sutimlimab values. Overall, sutimlimab was generally well tolerated in Part B. All 22 patients experienced ≥1 treatment-emergent adverse event (TEAE); 12 (54.5%) patients experienced ≥1 serious TEAE, including seven (31.8%) with ≥1 serious infection. Three patients discontinued due to a TEAE. No patients developed systemic lupus erythematosus or meningococcal infections. After cessation of sutimlimab, most patients reported adverse events consistent with recurrence of CAD. In conclusion, the CARDINAL 2-year results provide evidence of sustained sutimlimab effects for CAD management, but that disease activity reoccurs after treatment cessation. NCT03347396. Registered November 20, 2017. in press

BACKGROUND Rilzabrutinib, an oral, reversible covalent inhibitor of Bruton's tyrosine kinase, may increase platelet counts in patients with immune thrombocytopenia by means of dual mechanisms of action: decreased macrophage (Fcγ receptor)-mediated platelet destruction and reduced production of pathogenic autoantibodies. METHODS In an international, adaptive, open-label, dose-finding, phase 1-2 clinical trial, we evaluated rilzabrutinib therapy in previously treated patients with immune thrombocytopenia. We used intrapatient dose escalation of oral rilzabrutinib over a period of 24 weeks; the lowest starting dose was 200 mg once daily, with higher starting doses of 400 mg once daily, 300 mg twice daily, and 400 mg twice daily. The primary end points were safety and platelet response (defined as at least two consecutive platelet counts of ≥50×103 per cubic millimeter and an increase from baseline of ≥20×103 per cubic millimeter without the use of rescue medication). RESULTS Sixty patients were enrolled. At baseline, the median platelet count was 15×103 per cubic millimeter, the median duration of disease was 6.3 years, and patients had received a median of four different immune thrombocytopenia therapies previously. All the treatment-related adverse events were of grade 1 or 2 and transient. There were no treatment-related bleeding or thrombotic events of grade 2 or higher. At a median of 167.5 days (range, 4 to 293) of treatment, 24 of 60 patients (40%) overall and 18 of the 45 patients (40%) who had started rilzabrutinib treatment at the highest dose met the primary end point of platelet response. The median time to the first platelet count of at least 50×103 per cubic millimeter was 11.5 days. Among patients with a primary platelet response, the mean percentage of weeks with a platelet count of at least 50×103 per cubic millimeter was 65%. CONCLUSIONS Rilzabrutinib was active and associated with only low-level toxic effects at all dose levels. The dose of 400 mg twice daily was identified as the dose for further testing. Overall, rilzabrutinib showed a rapid and durable clinical activity that improved with length of treatment.

Chronic/refractory immune thrombocytopenia (ITP) is a rare and pathophysiologically heterogeneous disorder with variable responsiveness to available treatments. Sutimlimab, a first-in-class humanized monoclonal anti-C1s IgG4 antibody, selectively inhibits the classical pathway. This phase 1 study (NCT03275454) assessed the safety, efficacy, pharmacokinetics, and pharmacodynamics of biweekly sutimlimab in patients with chronic/refractory ITP with an inadequate response to ≥2 therapies (platelet count ≤ 30 × 109/L). Twelve patients (median age 42 years) received sutimlimab for a median of 20.5 weeks followed by a median 2-week washout period (part A). In part B, 7 of the 12 eligible patients received sutimlimab retreatment for a median of 113 weeks. In part A, the mean (standard deviation) platelet count increased from 25 × 109/L (17) to 54 × 109/L (60) 24 hours after starting sutimlimab, maintaining ≥50 × 109/L throughout part A. Five patients (42%) achieved durable platelet count responses (≥50 × 109/L in ≥50% of follow-up visits) and 4 achieved complete response (platelet count ≥100 × 109/L). The mean platelet count returned to baseline during washout and increased upon retreatment in part B. The mean platelet count improvements accompanied the rapid inhibition of the classical pathway. There were 74 treatment-emergent adverse events in part A (n = 10) and 70 in part B (n = 6). Five serious adverse events were observed; 1 event (migraine) was assessed by the investigator as related to sutimlimab. These results demonstrated that in some patients with ITP, autoantibodies activate the classical complement pathway, accelerating platelet destruction or impairing platelet production and contributing to treatment failure. Thus, C1s inhibition may be a safe and beneficial therapeutic approach for patients with chronic/refractory ITP.

Background & aims Upregulation of hepatic delta-aminolevulinic acid synthase 1 with accumulation of potentially toxic heme precursors delta-aminolevulinic acid and porphobilinogen is fundamental to the pathogenesis of acute hepatic porphyria. Aims evaluate long-term efficacy and safety of givosiran in acute hepatic porphyria. Methods Interim analysis of ongoing ENVISION study (NCT03338816), after all active patients completed their Month 24 visit. Patients with acute hepatic porphyria (≥12 years) with recurrent attacks received givosiran (2.5 mg/kg monthly) (n = 48) or placebo (n = 46) for 6 months (double-blind period); 93 received givosiran (2.5 mg or 1.25 mg/kg monthly) in the open-label extension (continuous givosiran, n = 47/48; placebo crossover, n = 46/46). Endpoints included annualized attack rate, urinary delta-aminolevulinic acid and porphobilinogen levels, hemin use, daily worst pain, quality of life, and adverse events. Results Patients receiving continuous givosiran had sustained annualized attack rate reduction (median 1.0 in double-blind period, 0.0 in open-label extension); in placebo crossover patients, median annualized attack rate decreased from 10.7 to 1.4. Median annualized days of hemin use were 0.0 (double-blind period) and 0.0 (open-label extension) for continuous givosiran patients and reduced from 14.98 to 0.71 for placebo crossover patients. Long-term givosiran led to sustained lowering of delta-aminolevulinic acid and porphobilinogen and improvements in daily worst pain and quality of life. Safety findings were consistent with the double-blind period. Conclusions Long-term givosiran has an acceptable safety profile and significantly benefits acute hepatic porphyria patients with recurrent attacks by reducing attack frequency, hemin use, and severity of daily worst pain while improving quality of life.

Current therapies for immune thrombocytopenia (ITP) are successful in providing a haemostatic platelet count in over two-thirds of patients. Still, some patients have an inadequate response and there is a need for other therapies. A number of novel therapies for ITP are currently being developed based upon the current pathophysiology of ITP. Many therapies are targetted at reducing platelet destruction by decreasing anti-platelet antibody production by immunosuppression with monoclonal antibodies targetted against CD40, CD38 and the immunoproteasome or physically reducing the anti-platelet antibody concentration by inhibition of the neonatal Fc receptor. Others target the phagocytic system by inhibiting FcγR function with staphylococcal protein A, hypersialylated IgG, polymeric Fc fragments, or Bruton kinase. With a recognition that platelet destruction is also mediated by complement, inhibitors of C1s are also being tested. Inhibition of platelet desialylation may also play a role. Other novel therapies promote platelet production with new oral thrombopoietin receptor agonists or the use of low-level laser light to improve mitochondrial activity and prevent megakaryocyte apoptosis. This review will focus on these novel mechanisms for treating ITP and assess the status of treatments currently under development. Successful new treatments for ITP might also provide a pathway to treat other autoimmune disorders.

Vascular inflammation, lipid metabolism, and thrombogenicity play a key role not only in atherogenesis but also in the development of acute coronary syndromes. Biomarkers associated with coronary high-risk plaques defined according to intravascular imaging have not been systematically studied. A total of 69 patients with coronary artery disease who underwent both optical coherence tomography and intravascular ultrasound imaging, and who provided blood specimens were included. Comprehensive biomarkers for inflammation, lipid, and coagulation were analyzed. Composite models sought biomarker patterns associated with thin-cap fibroatheroma (TCFA) and "high-risk plaques" (TCFA and large plaque burden). Two different composite models were developed for TCFA, based on the finding that high sensitivity C-reactive protein (hsCRP), plasminogen activator inhibitor-1, fibrinogen, IL-6, homocysteine and amyloid A levels were elevated, and high-density lipoprotein cholesterol (HDL) and bile acid levels were decreased in these patients. Both composite models were highly accurate for detecting patients with TCFA (area under curve [AUC]: 0.883 in model-A and 0.875 in model-B, both p 0.001). In addition, creatinine, hsCRP, fibrinogen, tumor necrosis factor-α, IL-6, homocysteine, amyloid A, HDL, prothrombin, and bile acid were useful for detecting patients with "high-risk plaques". Two composite models were highly accurate for detection of patients with "high-risk plaques" (AUC: 0.925 in model-A and 0.947 in model-B, both p 0.001). Biomarkers useful for detection of patients with high-risk coronary plaques defined according to intravascular imaging have been identified. These biomarkers may be useful to risk stratify patients and to develop targeted therapy.Clinical Trial Registration https://www.umin.ac.jp/ctr/ , UMIN000041692. Biomarkers and high-risk plaques hsCRP, PAI-1, fibrinogen, IL-6, homocysteine, amyloid A, HDL, and bile acid were useful for detecting patients with TCFA. hsCRP, fibrinogen, IL-6, homocysteine, amyloid A, creatinine, TNFα, HDL, prothrombin, and bile acid were useful for detecting patients with "high-risk plaques" (plaque which has both TCFA and large plaque burden). White arrowhead denotes TCFA. Red and green dashed lines denote lumen area and external elastic membrane area, respectively.

Tungsten has recently emerged as a potential toxicant and is known to heterogeneously deposit in bone as reactive polytungstates. Zinc, which accumulates in regions of bone remodeling, also has a heterogenous distribution in bone. Determining the local concentrations of these metals will provide valuable information about their mechanisms of uptake and action. A series of bone (BN), 7:3 hydroxyapatite:collagen (HC), and hydroxyapatite (HA) standards were spiked with tungsten and zinc and used as calibration standards for laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis of bone tissue. The analytical performance of these standards was studied and validated at different step sizes using NIST SRM 1486 Bone Meal. The effect of matrix-matched calibration was assessed by comparing the calibration with BN and HC standards, which incorporate both inorganic and organic components of bone, to that of HA standards. HC standards were found to be more homogenous (RSD < 10%) and provide a linear calibration with better accuracy (R(2) > 0.994) compared to other standards. The limits of detection for HC at a 15 μm step size were determined to be 0.24 and 0.012 μg g(−1) for zinc and tungsten, respectively. Using this approach, we quantitatively measured zinc and tungsten deposits in the femoral bone of a mouse exposed to 15 μg mL(−1) tungsten for four weeks. Localized concentrations of zinc (942 μg g(−1)) and tungsten (15.7 μg g(−1)) at selected regions of enrichment were substantially higher than indicated by bulk measurements of these metals.

Tungsten is incorporated in many industrial goods, military applications and medical devices due to its ability to impart flexibility, strength and conductance to materials. Emerging evidence has questioned the safety of tungsten exposure as studies have demonstrated it can promote tumour formation, induce pulmonary disease and alter immune function. Although tungsten is excreted from the body it can accumulate in certain organs such as the brain, colon, liver, kidneys, spleen and bones, where most of the bioaccumulation occurs. Whether prolonged tungsten exposure leads to accumulation in other tissues is unknown. The present study demonstrated that mice exposed to 15 ppm sodium tungstate for 4 weeks in their drinking water showed comparable accumulation in both the bony vertebrae and intervertebral discs (IVDs). Lumbar IVD height was significantly reduced in tungsten-exposed mice and accompanied by decreased proteoglycan content and increased fibrosis. In addition to catabolic enzymes, tungsten also increased the expression of the inflammatory cytokines IL-1β and tumour necrosis factor (TNF)-α as well as the neurotrophic factors nerve growth factor (NGF) and brain-derived nerve factor (BDNF) in IVD cells. Tungsten significantly increased the presence of nociceptive neurons at the endplates of IVDs as observed by the expression of calcitonin gene-related peptide (CGRP) and anti-protein gene product 9.5 (PGP9.5) in endplate vessels. The present study provided evidence that tungsten may enhance disc degeneration and fibrosis as well as increase the expression of markers for pain. Therefore, tungsten toxicity may play a role in disc degeneration disease.

Inherently chiral calix[4]arenes with C4-symmetry are extremely rare and difficult to synthesise, severely hampering any effort to expand on their potential as chiral supramolecular catalysts and building blocks. Herein we report a reaction of a tetracarbamate calix[4]arene with NBS which results in a high yield of an inherently chiral calix[4]arenes with C4-symmetry. Furthermore, employing a chiral N-Boc proline moiety allows for separation of the diastereomers formed, thus obtaining the pure enantiomers after hydrolysis. The enantiomers could be assigned based on the CD spectra and DFT calculated values.

Background Gaucher disease (GD) manifests heterogeneously and other conditions are often misdiagnosed in its place, leading to diagnostic delays. The Gaucher Earlier Diagnosis Consensus (GED‐C) initiative proposed a point‐scoring system (PSS) based on the signs and covariables that are most indicative of GD to help clinicians identify which individuals to test for GD. Aims To validate the PSS retrospectively in a test population including patients with GD and other conditions with overlapping manifestations. Methods Four cohorts of adults with GD, liver disease, haematological malignancy or immune thrombocytopenia were identified from hospital records. Clinical data were audited for GED‐C factors identified as potentially indicative of GD and aggregate scores calculated (sum of scores/number of factors) based on published PSS weightings. Threshold discriminatory PSS scores, sensitivity and specificity were determined by receiver‐operating characteristic analysis. Results Among 100 patients (GD, n = 25; non‐GD, n = 75), analyses based on 11 possible factors estimated group mean (standard deviation) PSS scores of: GD (n = 14), 1.08 (0.25); non‐GD (n = 38), 0.58 (0.31). Mean between‐group difference (95% confidence interval) was −0.49 (−0.68, −0.31) and area under the receiver‐operating characteristic analysis curve (95% confidence interval) was 0.88 (0.78, 0.97). A threshold PSS score of 0.82 identified all 14 patients with GD in the analysis set (100% sensitivity) and 27 of 38 patients in the non‐GD group (71% specificity). Patients with liver disease and haematological malignancy were most likely to have manifestations overlapping GD. Conclusions Preliminary validation of the GED‐C PSS discriminated effectively between patients with GD and those with overlapping signs.

Introduction: Three distinct phases are recognized in immune thrombocytopenia (ITP): newly diagnosed (≤3 months after diagnosis), persistent (>3–12 months after diagnosis), and chronic (>12 months)...

Introduction: The thrombopoietin receptor agonists (TPO-RAs) are a class of drugs that have been FDA-approved for immune thrombocytopenia (ITP), periprocedural thrombocytopenia in patients with chronic liver disease (CLD), aplastic anemia, and thrombocytopenia associated with antiviral treatment of hepatitis C. Avatrombopag is a TPO-RA that is currently FDA-approved for ITP and periprocedural thrombocytopenia in patients with CLD and is currently undergoing evaluation for chemotherapy-induced thrombocytopenia (CIT) in an international phase III clinical trial. Areas covered: This paper summarizes the chemistry, pharmacodynamics, and pharmacokinetics of avatrombopag. In addition, the authors review the efficacy and safety of avatrombopag, covering clinical trials in patients with ITP and in patients with CLD scheduled to undergo a procedure. Expert opinion: Avatrombopag has demonstrated efficacy in patients with ITP. With its low side-effect burden, absence of hepatotoxicity, ease of use as an oral medication, and lack of food-drug interactions, avatrombopag is a favorable option for ITP, though there is a lack of long-term safety data. In periprocedural thrombocytopenia in patients with CLD, avatrombopag is comparable to lusutrombopag, another TPO-RA. Finally, the results of the study of avatrombopag in CIT are eagerly awaited, as there are no currently approved medications for this indication in the USA.

Introduction Coronavirus disease 2019 (COVID‐19) may cause a hypercoagulable state. The D‐dimer is frequently elevated in COVID‐19, but other markers of coagulation activation, including the prothrombin fragment 1.2 (PF1.2) are poorly described. Methods We studied hospitalized adults with COVID‐19 and PF1.2 measurement performed at any time during hospitalization. We evaluated the relationship between PF1.2 and synchronously measured D‐dimer. We utilized receiver operating characteristic (ROC) analysis to evaluate optimal thresholds for diagnosing thrombosis and multivariable logistic regression to evaluate association with thrombosis. Results 115 patients were included [110 (95.7%) critically ill]. PF1.2 and D‐dimer were moderately positively correlated (r=0.542, P523 pmol/L: 69.2% sensitivity, 67.7% specificity; >924 pmol/L: 37.9% sensitivity, 87.8% specificity). In multivariable analysis, a PF1.2 >500 pmol/L was significantly associated with VTE [adjusted odds ratio (OR) 4.26, 95% CI, 1.12‐16.21, P=0.034] and any thrombotic manifestation (adjusted OR 3.85, 95% CI, 1.39‐10.65, P=0.010); conversely, synchronously measured D‐dimer was not significantly associated with thrombosis. 90.6% of patients with a non‐elevated PF1.2 result did not develop VTE. Conclusions PF1.2 may be a useful assay, and potentially more discriminant than D‐dimer, in identifying thrombotic manifestations in hospitalized patients with COVID‐19. This article is protected by copyright. All rights reserved.

Chemotherapy-induced thrombocytopenia (CIT) frequently complicates cancer treatment causing chemotherapy treatment delays, dose reductions, and discontinuation. There is no US Food and Drug Administration (FDA)-approved agent available to manage CIT. This study retrospectively evaluated patients with CIT treated on institutional romiplostim treatment pathways at four US centers. The primary outcome was achievement of a romiplostim response (median on-romiplostim platelet count ≥75x109/L and ≥30x109/L above baseline). Secondary outcomes included time to platelet count ≥100x109/L and rates of the following: platelet count

Patients with relapsed warm antibody autoimmune hemolytic anemia (wAIHA) have limited treatment options. Fostamatinib is a potent, orally administered spleen tyrosine kinase inhibitor approved in the United States and Europe for the treatment of adults with chronic immune thrombocytopenia (ITP). This phase 2 study evaluated the response to fostamatinib, administered at 150 mg BID orally with or without food in adults with wAIHA and active hemolysis with hemoglobin (Hgb)10 g/dL who had failed at least one prior treatment. Hemoglobin levels and safety assessments were performed at visits every 2 weeks. The primary endpoint was Hgb10 g/dL with an increase of ≥2 g/dL from baseline by week 24 without rescue therapy or red blood cell transfusion. Eleven of 24 (46%) patients achieved the primary endpoint. Increases in median Hgb were detected at week 2 and sustained over time. Median lactate dehydrogenase levels and reticulocyte counts generally declined over time with little change in median haptoglobin levels. The most common adverse events (AEs) were diarrhea (42%), fatigue (42%), hypertension (27%), dizziness (27%), and insomnia (23%). AEs were manageable and consistent with the fostamatinib safety database of over 3900 patients across multiple diseases (rheumatoid arthritis, B-cell lymphoma, COVID-19, and ITP). No new safety signals were detected. Fostamatinib may be a promising therapeutic option for wAIHA. A randomized, double-blind, phase 3 study is nearing completion.

Patients with cold agglutinin disease (CAD) experience fatigue and poor quality of life. However, previous CAD-related studies have not explored patient-reported outcomes such as the Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue. Sutimlimab, a C1s complement inhibitor, has been shown to halt haemolysis in CAD. Here, we present 26-weeks’ patient-reported data from CARDINAL Part A (ClinicalTrials.gov, NCT03347396), which assessed efficacy and safety of sutimlimab in patients with CAD and recent history of transfusion. Aside from measuring changes in haemolytic markers, FACIT-Fatigue was measured at the treatment assessment timepoint (TAT; average of weeks 23, 25, and 26). Exploratory endpoints included the change in EuroQol 5-dimension 5-level questionnaire (EQ-5D-5L) and the 12-Item Short Form Health Survey (SF-12) at TAT, and Patient Global Impression of Change (PGIC), and Patient Global Impression of (fatigue) Severity (PGIS) at week 26. Mean (range) FACIT-Fatigue scores increased from 32.5 (14.0–47.0) at baseline (a score indicative of severe fatigue) to 44.3 (28.0–51.0) at TAT. Considerable improvements were reported for EQ-5D-5L at TAT, SF-12 scores at TAT, and PGIC and PGIS scores at week 26. Sutimlimab treatment resulted in sustained improvements in symptoms of fatigue and overall quality of life in patients with CAD. NCT03347396. Registered 20 November, 2017.

Regulatory agencies are increasingly considering real-world evidence (RWE) to support label expansions of approved medicines. We conducted a comparative effectiveness study to emulate a proposed randomized trial of romiplostim versus standard-of-care (SOC) therapy among patients with recently diagnosed (≤ 12 months) immune thrombocytopenia (ITP), that could support expansion of the romiplostim label. We discuss challenges that we encountered and solutions that were developed to address those challenges. Study size was a primary concern, particularly for romiplostim initiators, given the rarity of ITP and the stringent trial eligibility criteria. For this reason, we leveraged multiple data sources (Nordic Country Patient Registry for Romiplostim; chart review study of romiplostim initiators in Europe; Flatiron Health EMR linked with MarketScan claims). Additionally, unlike the strictly controlled clinical trial setting, platelet counts were not measured at regular intervals in the observational data sources, and therefore the endpoint of durable platelet response often used in trials could not be reliably measured. Instead, the median platelet count was chosen as the primary endpoint. Ultimately, while we observed a slightly higher median platelet count in the romiplostim group versus SOC, precision was limited because of small study size (median difference was 11 x 109 /L (CI: -59, 81)). We underscore the importance of conducting comprehensive feasibility assessments to identify fit-for-purpose data sources with sufficient sample size, data elements, and follow-up. Beyond technical challenges, we also discuss approaches to increase the credibility of RWE, including systematic incorporation of clinical expertise into study design decisions, and separation between decision-makers and the data.

Introduction Acute hepatic porphyria (AHP) is a family of rare genetic diseases due to enzyme defects in hepatic heme biosynthesis. ENVISION is an ongoing phase 3 study, evaluating efficacy and safety of givosiran in symptomatic AHP patients. Objective Describe efficacy and safety resuts of the ENVISION 18-month OLE period. Methods Exploratory efficacy (composite porphyria attacks, ALA/PBG levels, hemin use, and missed days of work) and safety measures in the OLE were assessed. Analyses were descriptive and represent the timepoint after which all patients completed at least their Month 18 visit (01/10/2020). Results Ninety-four patients completed the DB period, and 93 patients entered the OLE (placebo/givosiran = 46; givosiran/givosiran = 47). Mean exposure to givosiran was 12.97 [SD = 3.6] months for placebo/givosiran and 18.86 [3.6] months for givosiran/givosiran, with maximum exposure of 25.1 months. Continued treatment in givosiran/givosiran patients led to a median annualized attack rate (AAR) of 0.58 (range: 0–16.2) through Month 18. Patients in the placebo/givosiran group had an AAR of 1.62 (range: 0–11.8) after receiving givosiran for ≥12 months during the OLE period, compared with 10.65 (range: 0–51.6) whilst receiving placebo during the 6-month DB period. Sustained ALA/PBG lowering during the OLE was accompanied by sustained reductions in hemin use, and more than half of the placebo/givosiran patients experienced 0 days of hemin use. There was a decrease in the number of work days missed in the past 4 weeks at Month 6 (mean = 6.7 days [SD = 7.8], n = 20/46) compared with Month 18 (2.5 [5.1], n = 23/46), for patients in the placebo/givosiran group who were able to work. The most common related adverse events (AEs) observed during givosiran treatment were injection site reactions, nausea and fatigue. Hepatic and renal AEs were both reported in 17% of patients each during givosiran treatment. No new safety concerns occurred in the OLE period. Conclusion In the ongoing OLE period of the ENVISION study, patients receiving long-term treatment with givosiran demonstrated a durable response in clinical efficacy, across a wide range of clinical parameters. Following the initial 6 months of givosiran treatment during the OLE, placebo/givosiran patients had a similar clinical response to that observed in givosiran/givosiran patients in the OLE period through Month 18. The safety profile of givosiran remained acceptable and consistent with that previously observed.

Thrombopoietin regulates platelet production through activation of the thrombopoietin receptor (TPO-R). TPO-R agonists (TPO-RAs) are available to treat thrombocytopenia in chronic immune thrombocytopenia (ITP), chronic liver disease (CLD) patients who are undergoing a procedure, severe aplastic anemia (SAA), and hepatitis C virus (HCV) infection. There are four TPO-RAs approved in the US and Europe: romiplostim (ITP), eltrombopag (ITP, SAA, HCV), avatrombopag (ITP, CLD), and lusutrombopag (CLD). It is important to understand pharmacological characteristics of these agents when evaluating treatment options. Avatrombopag interacts with the transmembrane domain of the TPO-RA and does not compete with endogenous thrombopoietin for TPO-R binding. Structural differences between avatrombopag and other TPO-RAs may impart differential downstream effects on cell signaling pathways, potentially resulting in clinically relevant differences in outcome. Avatrombopag has a favorable pharmacological profile with similar exposure in Japanese, Chinese, or Caucasian patients and no drug-drug interactions, food interactions, or potential for chelation.

Cases of de novo immune thrombocytopenia (ITP), including a fatality, following SARS-CoV-2 vaccination in previously healthy recipients led to studying its impact in preexisting ITP. In this study, 4 data sources were analyzed: the Vaccine Adverse Events Reporting System (VAERS) for cases of de novo ITP; a 10-center retrospective study of adults with preexisting ITP receiving SARS-CoV-2 vaccination; and surveys distributed by the Platelet Disorder Support Association (PDSA) and the United Kingdom (UK) ITP Support Association. Seventy-seven de novo ITP cases were identified in VAERS, presenting with median platelet count of 3 [1-9] ×109/L approximately 1 week postvaccination. Of 28 patients with available data, 26 responded to treatment with corticosteroids and/or intravenous immunoglobulin (IVIG), and/or platelet transfusions. Among 117 patients with preexisting ITP who received a SARS-CoV-2 vaccine, 19 experienced an ITP exacerbation (any of: ≥50% decline in platelet count, nadir platelet count 20% decrease from baseline, and/or use of rescue therapy) following the first dose and 14 of 70 after a second dose. Splenectomized persons and those who received 5 or more prior lines of therapy were at highest risk of ITP exacerbation. Fifteen patients received and responded to rescue treatment. In surveys of both 57 PDSA and 43 UK patients with ITP, prior splenectomy was associated with worsened thrombocytopenia. ITP may worsen in preexisting ITP or be identified de novo post–SARS-CoV2 vaccination; both situations responded well to treatment. Proactive monitoring of patients with known ITP, especially those postsplenectomy and with more refractory disease, is indicated.

Background. Warm antibody autoimmune hemolytic anemia (wAIHA) is a rare disorder that can be potentially serious. In wAIHA, autoantibodies react with protein antigens on red blood cells (RBCs) at body temperature, leading to RBC phagocytosis and destruction by Fcg receptor-bearing macrophages in a spleen tyrosine kinase (SYK) dependent signaling pathway (see figure). Fostamatinib is a potent oral SYK inhibitor, approved for the treatment of chronic immune thrombocytopenia (ITP). Fostamatinib prevents platelet destruction in ITP through inhibition of SYK-dependent platelet phagocytosis by Fcγ receptor-bearing macrophages. Fostamatinib was evaluated in a phase 2, open-label, multicenter study (NCT02612558) for the treatment of wAIHA. Results of the study demonstrated that 11 of 25 (44%) patients had markedly improved hemoglobin (Hgb) levels after fostamatinib treatment. Adverse events (AEs) were consistent with those in the fostamatinib safety database of >4000 patients across multiple diseases. Based on the results of the phase 2 study, a phase 3 randomized, double-blind, placebo-controlled, global study (NCT03764618) was initiated to investigate the safety and efficacy of fostamatinib in patients with wAIHA. The phase 3 study began enrolling patients this year and intends to enroll approximately 90 patients at 103 sites in 22 countries across North America, Europe, and Australia. This is the first randomized, double-blind, placebo-controlled, phase 3 study to evaluate a SYK inhibitor for the treatment of wAIHA (see diagram). Study Design and Methods Inclusion Criteria include: Age ≥18;Diagnosis of primary or secondary wAIHA (documented by an IgG or IgA positive direct antiglobulin test [DAT]);failure of ≥1 prior treatment for wAIHA;Haptoglobin ULN (upper limit of normal) or lactate dehydrogenase (LDH) >ULN;Baseline hemoglobin level ≤9 g/dL or, if hemoglobin is >9 g/dL to Exclusion Criteria include: Presence of other forms of AIHA;Uncontrolled or insufficiently controlled hypertension;Neutrophil count 1.5 x ULN. Eligible patients will be randomized 1:1 to fostamatinib or placebo for 24 weeks. Randomization will be stratified by concomitant steroid use and severity of anemia at baseline. The starting dose of fostamatinib is 100 mg BID and will be increased to 150 mg BID at Week 4, based on tolerability. The dose may be reduced in the event of dose-limiting AEs. At screening, patients may continue selected concurrent wAIHA therapies including steroids (maximum of 2 therapies) throughout the 24-week study period. A steroid taper protocol will allow reduced used of steroids in patients who have a hemoglobin response. Rescue therapy will be allowed as needed. Patients who complete the phase 3 study can rollover to an open-label extension study. The efficacy endpoints will include hemoglobin response, defined as a hemoglobin level ≥10 g/dL with a ≥2 g/dL increase from baseline (Day 1) in the absence of rescue therapy; duration of hemoglobin response; and the need for wAIHA rescue treatment. The safety endpoints will include the incidence of adverse events. Patients will be evaluated in the clinic, including safety and laboratory assessments, at two-week intervals. Statistics: A sample size of 90 subjects (randomized 1:1) would be required to provide 80% power to detect a difference in the response between the active and placebo groups using the Cochran-Mantel-Haenszel test at a two-sided significance level of 0.05 (based on results of the phase 2 study). The response rate will be compared between groups using a chi-square test adjusted for randomization stratification factors. Current enrollment status: As of July 2, 2020, 83 sites are open to screening (subject to local regulations about the COVID-19 pandemic), and 43 patients have been randomized. Most patients (88%) had primary wAIHA, 12% had secondary disease including chronic lymphocytic leukemia, monoclonal B cell lymphocytosis, scleroderma, smoldering Waldenström's macroglobulinemia, and systemic lupus erythematosus in 1 patient each. The median age at baseline is 61 years (range 28-87), and 63% are female. Figure Disclosures Cooper: Amgen: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau. Numerof:Rigel: Current Employment, Current equity holder in publicly-traded company. Tong:Rigel: Current Employment, Current equity holder in publicly-traded company. Kuter:Incyte: Consultancy, Honoraria; Genzyme: Consultancy, Honoraria; Immunovant: Consultancy, Honoraria; Momenta: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Dova: Consultancy, Honoraria; Merck Sharp Dohme: Consultancy, Honoraria; UCB: Consultancy, Honoraria; Up-To-Date: Consultancy, Honoraria, Patents & Royalties; Zafgen: Consultancy, Honoraria; Sanofi (Genzyme): Consultancy, Honoraria; Shionogi: Consultancy, Honoraria; Shire: Consultancy, Honoraria; Principia: Consultancy, Research Funding; Protalix Biotherapeutics: Consultancy; Shionogi: Consultancy; Actelion (Syntimmune): Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Daiichi Sankyo: Consultancy, Honoraria; Agios: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Alnylam: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Amgen: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Argenx: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Immunovant: Other: Travel Expenses, Research Funding; Caremark: Consultancy, Honoraria; CRICO: Consultancy, Honoraria; Kezar Life Sciences, Inc: Other, Research Funding; Principia Biopharma: Consultancy, Honoraria, Other, Research Funding; Protalex: Consultancy, Honoraria, Other, Research Funding; Rigel: Consultancy, Honoraria, Other, Research Funding; Takeda (Bioverativ): Consultancy, Honoraria, Other, Research Funding; Protalex: Consultancy, Honoraria, Research Funding; Kyowa-Kirin: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Platelet Disorder Support Association: Consultancy, Honoraria.

Platelet autoantibody (PA) testing has previously shown poor sensitivity for immune thrombocytopenia (ITP) diagnosis, but no previous study used both 2011 American Society of Hematology (ASH) guidelines for ITP diagnosis and 2012 International Society on Thrombosis and Haemostasis (ISTH) PA testing recommendations. We therefore performed a comprehensive retrospective study of PA testing in adult patients with ITP strictly applying these criteria. Of 986 PA assays performed, 485 assays in 368 patients met criteria and were included. Sensitivity and specificity of a positive test result for diagnosis of active ITP (n = 228 patients) were 90% and 78%, respectively. Sensitivity and specificity of a negative test result for clinical remission (n = 61 assays) were 87% and 91%. Antibodies against both glycoprotein IIb (GPIIb)/IIIa and GPIb/IX were required for the presence of antibodies against GPIa/IIa in patients with ITP. Logistic regression analysis revealed that more positive autoantibodies predicted more severe disease (relative to nonsevere ITP, relative risk ratio for severe ITP and refractory ITP was 2.27 [P < .001] and 3.09 [P < .001], respectively, per additional autoantibody); however, serologic testing did not meaningfully predict treatment response to glucocorticoids, intravenous immunoglobulin, or thrombopoietin receptor agonists. Sixty-four patients with ITP had multiple PA assays performed longitudinally: all 10 patients achieving remission converted from positive to negative serologic results, and evidence for epitope spreading was observed in 35% of patients with ongoing active disease. In conclusion, glycoprotein-specific direct PA testing performed using ISTH recommendations in patients meeting ASH diagnostic criteria is sensitive and specific for ITP diagnosis and reliably confirms clinical remission. More glycoproteins targeted by autoantibodies predicts for more severe disease.

Treating deuterohemin, chloro(deuteroporphyrinato)iron(III), with a non-coordinating base in DMSO/methanol allows for the isolation of [(deuteroporphyrinato)iron(III)]2 , deuterohematin anhydride (DHA), an analogue of malaria pigment, the natural product of heme detoxification by malaria. The structure of DHA obtained from this solvent system has been solved by X-ray powder diffraction analysis and displays many similarities, yet important structural differences, to malaria pigment. Most notably, a water molecule of solvation occupies a notch created by the propionate side chains and stabilizes a markedly bent propionate ligand coordinated with a long Fe-O bond, and a carboxylate cluster associated with water molecules is generated. Together, these features account for its increased solubility and more open structure, with an increased porphyrin-porphyrin separation. The IR spectroscopic signature associated with this structure also accounts for the strong IR band at 1587 cm-1 seen for many amorphous preparations of synthetic malaria pigment, and it is proposed that stabilizing these structures may be a new objective for antimalarial drugs. The important role of the vinyl substituents in this biochemistry is further demonstrated by the structure of deuterohemin obtained by single-crystal X-ray diffraction analysis.

The thrombopoietin receptor agonist romiplostim is approved for second-line use in chronic immune thrombocytopenia (ITP), but its effects in patients with ITP for ≤1 year are not well characterized. This analysis of pooled data from 9 studies included patients with ITP for ≤1 year (n = 311) or >1 year (n = 726) who failed first-line treatments and received romiplostim, placebo or standard of care. In subgroup analysis by ITP duration, patient incidences for platelet response at ≥75% of measurements were higher for romiplostim [ITP ≤1 year: 74% (204/277); ITP >1 year: 71% (450/634)] than for placebo/standard of care [ITP ≤1 year: 18% (6/34); ITP >1 year: 9% (8/92)]. Of patients with ≥9 months on study, 16% with ITP ≤1 year and 6% with ITP >1 year discontinued romiplostim and maintained platelet counts ≥50 × 109 /l for ≥6 months without ITP treatment (treatment-free remission). Independent of ITP duration, rates of serious adverse events and bleeding were lower with romiplostim than placebo/standard of care and thrombotic events occurred at similar rates. In this analysis, romiplostim and placebo/standard of care had similar safety profiles and romiplostim increased platelet counts in patients with either ITP ≤1 year or ITP >1 year, with more treatment-free remission in those with ITP ≤1 year.

Summary There is concern that COVID‐19 vaccination may adversely affect immune thrombocytopenia (ITP) patients. Fifty‐two consecutive chronic ITP patients were prospectively followed after COVID‐19 vaccination. Fifteen percent had no worsening of clinical symptoms but no post‐vaccination platelet count; 73% had no new symptoms and no significant platelet count decline. However, 12% had a median platelet count drop of 96% within 2–5 days post vaccination with new bleeding symptoms; after rescue therapy with corticosteroids +/− intravenous immunoglobulin (IVIG), platelets recovered to >30 × 109/l a median three days later. ITP exacerbation occurred independently of remission status, concurrent ITP treatment, or vaccine type. Safety of a second vaccine dose needs careful assessment.